3929743
Pregunta 1
Pregunta
Membrane characteristics
Respuesta
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Sheet like structures, two molecules thick, form closed boundaries
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composed of lipids and proteins,
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noncovalent assemblies
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covalent assesmblies
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are fluid structures
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are fatty structures
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Most are electrically polarized
Pregunta 2
Pregunta
Membranes are asymmetric in that the outer surface is always different from the inner surface
Respuesta
- True
- False
Pregunta 3
Pregunta
Membrane lipids are
Respuesta
-
small amphipathic molecules that form closed bimolecular sheets that prevent the movement of polar or charged molecules.
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large amphipathic molecules that form closed bimolecular sheets that prevent the movement of polar or charged molecules.
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small amphipathic molecules that form closed molecular sheets that prevent the movement of polar or charged molecules.
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large amphipathic molecules that form closed molecular sheets that prevent the movement of polar or charged molecules.
Pregunta 4
Pregunta
Proteins serve to mitigate the impermeability of membranes and
Respuesta
-
allow movement of molecules and information across the cell membrane
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don't allow movement of molecules and information across the cell membrane
Pregunta 5
Pregunta
Fatty acid names are based on their parent hydrocarbons
Respuesta
- True
- False
Pregunta 6
Pregunta
Fatty acids
Respuesta
-
are chains of hydrogen bearing carbon atoms that have a carboxylic acid at one end and a methyl group at the other end
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are chains of hydrogen bearing carbon atoms that have a ketone at one end and a methyl group at the other end
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may be saturated or unsaturated
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usually numbered beginning with the carboxyl terminal carbon atom
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When double bonds present, they are commonly in the cis position
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Properties are dependent on chain length and degree of unsaturation
Pregunta 7
Pregunta
Fatty acids can also be numbered from the methyl carbon atom which is called the omega (ω) carbon.
Respuesta
- True
- False
Pregunta 8
Pregunta
Carbon atoms [blank_start]2[blank_end] and [blank_start]3[blank_end] are also referred to as α and β, respectively.
Respuesta
-
2
-
3
Pregunta 9
Pregunta
Fatty acids in biological systems usually contain an [blank_start]even[blank_end] number of carbon atoms, with the [blank_start]16[blank_end]- and [blank_start]18[blank_end]-carbon atom chains the most common.
Respuesta
-
even
-
odd
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16
-
15
-
18
-
17
Pregunta 10
Pregunta
In polyunsaturated fatty acids, the double bonds are separated by at least one
Respuesta
-
methylene group
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carboxylic acid
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ketone
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aldehyde
Pregunta 11
Pregunta
Long chain length and the presence of cis double bonds enhances the fluidity of fatty acids
Respuesta
- True
- False
Pregunta 12
Pregunta
What are the major class of membrane lipids
Respuesta
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Phospholipids
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Glycolipids
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Cholesterol
Pregunta 13
Pregunta
Phospholipids are composed of four components:
Respuesta
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fatty acids (1 or more), a platform, a carbon, and an alcohol.
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fatty acids (1 or more), a platform, a phosphate, and an alcohol.
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fatty acids (1 or more), a platform, a phosphate, and an nitrogen.
Pregunta 14
Pregunta
Two common platforms are [blank_start]glycerol[blank_end] and [blank_start]sphingosine[blank_end]
Respuesta
-
glycerol
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glycogen
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sphingosine
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sphinose
Pregunta 15
Pregunta
Phospholipids with a glycerol platform are called
Respuesta
-
phosphoglycerides
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phosphoglycerols
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phosphoglycogen
Pregunta 16
Pregunta
The common types of membrane lipids are
Respuesta
-
Phospholipids
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Glycolipids
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Cholesterol
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Carbohydrates
Pregunta 17
Pregunta
The major phospholipids are derived from
Respuesta
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Phosphatidate (diacylglycerol 3-phosphate)
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Phosphatidate (diacylglycerol 2-phosphate)
Pregunta 18
Pregunta
Phosphoglycerides are derived from phosphatidate by the formation of an ester bond between the phosphate and an alcohol
Respuesta
- True
- False
Pregunta 19
Pregunta
Glycolipids are
Respuesta
-
carbohydrate-containing lipids derived from sphingosine.
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carbohydrate-containing lipids derived from glycerol.
Pregunta 20
Pregunta
The carbohydrate in the glycolipid is linked to the secondary alcohol of sphingosine
Respuesta
- True
- False
Pregunta 21
Pregunta
What are the simplest glycolipids, containing only a single sugar
Respuesta
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Cerebrosides
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Gangliosides
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Monosaccharides
Pregunta 22
Pregunta
Gangliosides contain a branched chain of as many as
Respuesta
-
seven sugar molecules
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five sugar molecules
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three sugar molecules
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eight sugar molecules
Pregunta 23
Pregunta
The [blank_start]carbohydrate[blank_end] components of glycolipids are on the [blank_start]extracellular[blank_end] surface of the cell membrane, where they play a role in cell-cell recognition
Respuesta
-
carbohydrate
-
lipid
-
extracellular
-
intracellular
Pregunta 24
Pregunta
Cholesterol is a lipid based on a steroid nucleus
Respuesta
- True
- False
Pregunta 25
Pregunta
Cholesterol is a
Respuesta
-
a steroid that is modified on both ends by the attachment of a fatty acid chain and at the other end by a methyl group
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a steroid that is modified on one end by the attachment of a fatty acid chain and at the other end by a hydroxyl group
Pregunta 26
Pregunta
In membranes, the hydroxyl group interacts with phospholipid head groups
Respuesta
- True
- False
Pregunta 27
Pregunta
A membrane lipids is an
Respuesta
-
an amphipathic molecule containing a hydrophilic and hydrophobic moiety
-
an amphipathic molecule containing a hydrophilic moiety
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an amphipathic molecule containing a hydrophobic moiety
Pregunta 28
Pregunta
The fatty acid components provide the
Respuesta
-
hydrophobic properties
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hydrophilic properties
Pregunta 29
Pregunta
The alcohol and phosphate components are called the
Respuesta
-
polar head group, hydrophilic properties
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polar head groups, hydrophobic properties
Pregunta 30
Pregunta
Phospholipids and Glycolipids Readily form Bimolecular sheets in Aqueous Media
Respuesta
- True
- False
Pregunta 31
Pregunta
Membrane formation is a consequence of the amphipathic nature of the constituent lipid molecules.
Respuesta
- True
- False
Pregunta 32
Pregunta
Phospholipids are
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-
too large to form micelles
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too small to form micelles
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like glycolipids spontaneously form lipid bilayers in aqueous solutions
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like glycolipids nonspontaneously form lipid bilayers in aqueous solutions
Pregunta 33
Pregunta
The hydrophobic effect powers membrane formation, and van der Waals interactions between the [blank_start]hydrophobic[blank_end] tails stabilize membranes
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-
hydrophobic
-
hydrophillic
Pregunta 34
Pregunta
Integral membrane proteins
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composed of β strands that form a pore in the membrane.
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composed of α helices that form a pore in the membrane
Pregunta 35
Pregunta
What is an example of β strand–rich integral membrane protein.
Respuesta
-
bacterial protein porin
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Membrane spanning
Pregunta 36
Pregunta
The [blank_start]outside[blank_end] surface of porin, which interacts with the [blank_start]hydrophobic[blank_end] interior of the membrane, is composed of [blank_start]hydrophobic[blank_end] amino acids. The [blank_start]inside[blank_end] is [blank_start]polar[blank_end] and filled with water.
Respuesta
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outside
-
inside
-
hydrophobic
-
hydrophillic
-
hydrophobic
-
hydrophillic
-
inside
-
outside
-
polar
-
nonpolar
Pregunta 37
Pregunta
Membrane-spanning α helices are a common structural feature of integral membrane proteins.
Respuesta
- True
- False
Pregunta 38
Pregunta
Bacteriorhodopsin, a light-powered proton pump, is an integral membrane protein composed of eight membrane- spanning helices.
Respuesta
- True
- False
Pregunta 39
Pregunta
Only a portion of the enzyme prostaglandin H2 synthase-1 is embedded in the membrane.
Respuesta
- True
- False
Pregunta 40
Pregunta
The cyclooxygenase (COX) activity of prostaglandin H2 synthase-1 is dependent on a channel connecting the [blank_start]active site[blank_end] to the membrane interior.
Respuesta
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active site
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terminator site
Pregunta 41
Pregunta
What inhibits cyclooxygenase activity by obstructing the channel
Respuesta
-
Aspirin
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Xanax
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Klonopin
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Naproxen
Pregunta 42
Pregunta
Hydrophobic proteins can be made to associate with the membrane by attaching a hydrophillic group.
Respuesta
- True
- False
Pregunta 43
Pregunta
The fluid mosaic model allows
Respuesta
-
lateral movement but not rotation through the membrane
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rotation through the membrane
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vertical movement
Pregunta 44
Pregunta
The fluid mosaic model describes
Respuesta
-
membranes as two-dimensional solutions of oriented lipids and globular proteins
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membranes as two-dimensional solutions of oriented lipids and quartnary proteins
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membranes as two-dimensional solutions of oriented lipids and primary proteins
Pregunta 45
Pregunta
The lipids serve as a solvent and a permeability barrier
Respuesta
- True
- False
Pregunta 46
Pregunta
Lipids rapidly diffuse vertically in membranes, although transverse diffusion or flip-flopping is very rare without the assistance of enzymes
Respuesta
- True
- False
Pregunta 47
Pregunta
The prohibition of [blank_start]transverse[blank_end] diffusion accounts for the stability of membrane asymmetry.
Respuesta
-
transverse
Pregunta 48
Pregunta
Membrane fluidity is controlled
Respuesta
-
by fatty acid composition and carbohydrate content
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by fatty acid composition and cholesterol content
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by fatty acid composition and amino acid content
Pregunta 49
Pregunta
Cholesterol helps to maintain proper membrane fluidity in membranes in animals
Respuesta
- True
- False
Pregunta 50
Pregunta
No Biological membranes are asymmetric
Respuesta
- True
- False
Pregunta 51
Pregunta
The Na+-K+ pump illustrates
Respuesta
-
the principle of membrane asymmetry.
-
Pumps 3 Na+ out of the cell and 2 K+ into the cell by hydrolyzing ATP on the intracellular side of the membrane
-
Pumps 2 Na+ out of the cell and 3 K+ into the cell by hydrolyzing ATP on the extracellular side of the membrane
Pregunta 52
Pregunta
Some bacteria are enclosed by a single membrane surrounded by a cell wall.
Respuesta
- True
- False
Pregunta 53
Pregunta
Other bacteria are surrounded by two membranes, with a cell wall lying between them
Respuesta
- True
- False
Pregunta 54
Pregunta
Other bacteria are surrounded by two membranes, with a cell wall lying between them.The space between the two membranes is called the
Respuesta
-
periplasm
-
cytoplasm
-
mitochondria
Pregunta 55
Pregunta
With exception of plants, what cells do not have cell walls and area surrounded by a single membrane, the plasma membrane
Respuesta
-
Eukaryotic cells
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Prokaryotic cells
Pregunta 56
Pregunta
Cells can acquire molecules from their environment by receptor-mediated endocytosis.
Respuesta
- True
- False
Pregunta 57
Pregunta
The protein clathin helps to
Respuesta
-
internalize receptors bound to their cargo
-
receptor-mediated endocytosis
-
facilitate membrane fusion by forming tightly coiled four-helical bundles
Pregunta 58
Pregunta
Fusion of internal membranes with the plasma membrane allows the [blank_start]release[blank_end] of molecules, such as [blank_start]neurotransmitters[blank_end], from the cell
Respuesta
-
release
-
absorabance
-
neurotransmitters
-
serotonin
Pregunta 59
Pregunta
9. The internalization of iron-bound transferrin in association with the transferrin receptor is a example of
Respuesta
-
SNARE proteins
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receptor-mediated endocytosis
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protein clathrin
Pregunta 60
Pregunta
[blank_start]SNARE[blank_end] proteins facilitate membrane fusion by forming tightly coiled four-helical bundles.
Respuesta
-
SNARE
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